Switch



Sept. 9, 1947. D. G. CLIFFORD SWITCH Filed Oct. 28, 1942 ATTORNEY Patented Sept. 9, 1947 UN lTED' STATES PATENT OFFICE SWITCH v David Gordon Clifford, Montclair, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 28, 1942, Serial No. 463,663

6 Claims. l

This invention relates generally to switches,` and more particularly to automatic resonant cavity switches of the type generally referred to in the trade as TR. Boxes.

Devices of the general character above specined are used in connection with Wave guides in a system which includes a source of ultra high frequencyor micro-wave generation for promulgation of the ywave energy intoA space Where it is reflected. from an object, such as an airplane, and

returnsto the wave guide and to a receiver' connected therewith. The function of the TR.' BOX is to protect the receiver from the high power of the transmitted signal but to provide for passage of the returning weak signal to the receiver. The

general construction of TR Boxes includes .an

evacuated resonant chamber havingV windows looking in opposite directions into the wave guide axially thereof. Inclusion of such windowsand in. a manner .to permanently maintain theV vacuum within the4 chamber, has' presented a problem notV heretofore" `satisfactorily solved either from an economical manufacturing standpoint or from an efciency standpoint.

The present invention accordingly has forits general object the provision of a TR BOX overcoming the manufacturing and eiiiciency diiiiculties heretofore encountered. y

` More specifically, an object of the invention is to provide a switch as, characterized having improved window construction'.y

Closely related to the preceding object is the desideratum thai-,Window construction be provided which is practical for mass production oi the switches.

Another object of the invention is to provide a switch Y construction including windows and which will assure maintenance of desired evacuation of the resonant chamber.

A further object of the invention is to provide a construction made from a minimum number Ofparts and to maintain accuracy of dimensions of the asembly thereof.

Yet another object of the invention is to pro- Vide delicate4 but sturdytuning mechanism in a switch of the character indicated.

Still further objects of the invention will appear as the description progresses, both by direct mention thereof and by implication from the context.

Referring to the accompanying drawing in which like numerals ofl referenceindicate similar parts throughout the several views;

Figure 1 is asectio-nal `View on a plane'longi- `character and amount.

`convenience will be vView on une Iv-iv guide looking toward one of the Windows,` as on Y line VV of Fig. 1; and

Figures 6 and '7 are sectional Views similar to Fig. 2, showing modied constructions of shells.

In the specic embodiment of theinvention illustrated insai'd drawing, the switch is illustrated as comprising in general a cylindrical shell l0 composed of several parts more fully described hereinafter, the axis of said shell being perpendicular to and intersecting the center-line or axis of a wave guide Il of rectangular crosssection. Opposite end portions of the shell protrude at opposite sides of the Wave guide and the diameter of the shell is such that it physically blocks the entire internal passage of the wave guide. The shell has two Window `openings therein situated at diametrically opposite parts thereof and shown circular with their centers coincident with the center-line `of the waveguide. Energy in the wave guide at one side of the shell has to pass through said Windows I2 to enter the part of the wave guide at the other side of said shell. For effective operation of the switch, tle region within the shellfor that part thereof passing through the wave guide, is evacuated and in some instances charged with a gas of appropriate This `necessitates `that said region must be a closed chamber, and in the prior art, as well as in the present invention, the windows are sealed with a closure of suitable material, usually glass, which will `be transparent to the wave energy desired to passV therethrough. Thteconstruction and sealing ofv these closures constitutes a feature of the present invention.

Returning now fora more detailed description of the shell and its associated parts, the construction shown in Figures 1` to 5 inclusive comprises cylindrical end portions I3, I4 which for referred to as the upper and lower end sections respectively. Said sections are sho-wn of equal diameters and axially aligned with the inner ends or ends directed toward `each other within the wave guide but separatedfrom eachother a distance greater than the diameter of the windows and of the closures therefor. Spanning the distance between the inwardly section diametrically opposite each other and on a common axis. Said axis is represented by section line IV--IV and when the shell is assembled in the wave guide said axis is made coincident with the center line of the wave guide.

Said Windows I2 are covered with closures I6, I6, one for each, it being particularly noted that the application of said closures is from the outside of the assembled shell so that placing the closures may be delayed to be one of the final assembly operations. The said closures are preferably formed from plain discs of glass or other material transparent to the wave energy to be passed therethrough in use, and are of greater diameter than the windows so as to marginally overlap on the metal of the shell mid-section around said windows. Application of appropriate heat, by a fiame or otherwise, permits said glass discs to be bent to assume the same curvature as said mid-section of the shell and to engage the said metal around the entire peripheral margins of the closures at the margin of metal around the windows. Further appropriate application of heat to the closure will fuse the material thereof into sealing engagement with the metal. A preferred metal for mid-section I5 is cold rolled steel, soft iron or other metal preferably copper plated, and the glass is preferably Corning #1991, which is a high expansion, low density, lead glass. The glass forming the closure is of uniform thickness throughout the part seen through the opening of the window, the sealing covers a material area of metal thereby assuring secure and intimate attachment to the metal, and the sealing operation being readily effected from the exterior of the shell may be delayed as a final step before exhausting.

Said mid-section of the shell preferably comprises the resonant chamber, and its length is therefore critical, as mathematically length of a resonant chamber enters into the formula for resonant modes. Said mid-section is formed with an integral and fixed bottom wall I'l and with a metallic and flexible top wall I8. Said top wall is shown as a corrugated diaphragm having a peripheral flange sealed to the shell so as to position'the said top wall directly at the otherwise open end of the cup-like intermediate section. Both the top and bottom walls are provided with central openings through which protrude electrodes I9, 26 respectively, said electrodes being sealed to their respective walls so as to maintain the sealed condition of the chamber 2| formed by said section and its end walls. Said electrodes are directed toward each other on the axis of the shell with the ends of the electrodes in proximity to and on opposite sides of the afore-mentioned axis of the windows and center line of the wave guide represented by line IV-IV.

The upper electrode I9 is shown as of solid construction suitably flanged, as at 22 above the fiexible end wall I8 for sealing purposes with respect thereto, and provided with an upwardly extending threaded stem 23 for holding and adjusting the said electrode. A thumb-nut or adjusting knob 24 is provided with internal threads 25 to engage the threaded stem, said nut or knob also providing a coaxial hub 26 with external threads 2I thereon screwing through a fixed cap 28 carried at the end of the shell, Threads 25 and 2'I may both be in a common direction, for instance, right hand threads, but of different pitch or otherwise constructed to afford a differential in operation and obtain a fine adjustment of longitudinal movement of the stem and electrode with a considerable rotation of the nut or knob 24.

Lower electrode 20 is shown as a hollow cylinder with an open frusto-conical end and mounted within this cylinder between suitable ceramic or other insulative support 28 is a keep-alive electrode 29. The forward end of this keep-alive electrode is emissive, either inherently so by being tipped at 3D with radium or the like, or effectually emissive through a potential difference between said keep-alive electrode and the surrounding cylindrical electrode, in which event the keep-alive electrode is composed of or tipped with emissive material of usual or desired composition for emissive electrodes.

The bottom end of lower end-section I4 of the shell is flanged outward and projection welded to an end wall 3|, An eyeletl 32 is sealed to and through this end wall for a lead 33 to the keepalive electrode, said eyelet and lead being glassbeaded for sealing purposes. A tubulation 34 also is sealed through the end wall and constitutes the means for evacuation and for gas-charging if desired. Slits 38 or other openings may be provided in the bottom wall of the cup I5 for evacuation purposes. It will be understood that the interior of th'e shell from the said end wall 3| to the flexible diaphragm I8 is the region affected by evacuation and recharging but that the interior of the cup-like mid-section I5, namely, chamber 2 Iy is the resonant chamber for the device.

While the foregoing description has specifically referred to the shell as comprised of various parts, it is to be understood that many changes in construction and in steps of manufacture may be substituted within the present inventive concept. For instance, in Figure 6, the shell shown is composed of a full-length cylinder 35 and is provided in place of the end sections I3, I4 of the construction above described. This full-length cylinder has diametrically opposed holes 36 therein approximately midway of its length, said holes being larger than the window closure. Within the one-piece outer section represented by said cylinder 35, is situated the copper-plated iron cup-like mid-section I5 as in the previously described construction. It will be understood that in use the shell of Figure 6 is substituted for shell IIJ of the preceding figures and used with the electrodes, end walls and adjusting means shown therein.

In making the assembly of Figure 6, the windows I2 of the mid-section I5 are centered with respect to the larger holes 36 of the shell. The closures I6 will be softened, curved to fit and applied to th'e surface of the mid-section overlapping the windows as before, but in this instance will be within the holes 36 of the shell.

In the modified construction of Figure '7, upper end section I3a is shown integral with mid-section I5a, the lower end section I4 remaining as described in vconnection with Figure 1. Combined sections I3ct-I5a may be provided with a shoulder 31 corresponding in position and ei'- fect to the upper end of the mid-section, and may thus be utilized to maintain the critical lengthl of the resonant chamber when assembling the flexible diaphragm wall therewith.

It is to be understood that other modications and changes may be made which do not require specific showing herein as they icorne within the inventive concept fully described above and explicitly set forth inf the following claims.

I claim:

1. A switch comprising a cylindrical shell having a mid-section and another section of greater diameter overlapping the mid-section, said midsection comprising a resonant chamber, an end Wall for the overlapping section, an opposite end wall at the end of the mid-section, electrodes in the mid-section, said mid-section having windows a1; opposite sides thereof on an axis passing between th'e said electrodes, and closures for said windows.

2. A switch comprising a cylindrical shell having a mid-section and another section of greater diameter overlapping the mid-section, said midsection comprising a resonant chamber, an end wall for the overlapping section, a flexible diaphragm constituting an opposite end wall at the end of the mid-section, electrodes in the midsection of which one electrode is carried by said flexible diaphragm, said mid-section having windows at opposite sides thereof on an axis passing between the said electrodes, and closures for said windows.

3. A switch comprising a resonator having a cylindrical shell, opposed electrodes in said shell coaxial therewith, said electrodes being longitudinally separated one from the other providing a gap therebetween, said shell having windows in opposite sides thereof centered on a diameter of the shell transverse to said electrodes and opposite said gap, said windows being adapted one to admit wave energy into said resonator and the second to pass wave energy to the exterior of the resonator, said electrodes constructed and arranged for disrupting resonance in said resonator of high power wave energy and preventing outward propagation through the second window of high power wave energy,

4. A switch comprising a resonator having a cylindrical shell, opposed electrodes in said shell coaxial therewith, said electrodes being longitudinally separated one from the other providing a gap therebetween, one said electrode being hollow, a keep-alive electrode within the hollow electrode, said shell having windows in opposite sides thereof centered on a diameter of the shell transverse to said electrodes and opposite said gap, said windows being adapted one to admit wave energy into said resonator and the second to pass wave energy to the exterior of the resonator, said electrodes constructed and arranged for disrupting resonance in said resonator of high power wave energy and preventing outward propagation through the second window of high power wave energy.

5. In combination, a hollow Wave guide having an internal passage, a discontinuity in said passage transversely of and completely blocking the same, said discontinuity comprising a resonator having its length in direction of and substantially equal to cross sectional height of the wave guide, said resonator having windows looking into said wave guide in opposite directions from the resonator, and a window-closure for each window permeable to electromagnetic wave propagation in the wave guide from one side of the discontinuity to the other.

6. In combination, a hollow wave guide having an internal passage, a discontinuity in said passage transversely of and completely blocking the same, said discontinuity comprising a resonator having its length in direction of and substantially equal to cross sectional height of the wave guide, said resonator having windows looking from said resonator in opposite directions into said wave guide at the part thereof central with respect to the wave guide and of less area than the cross sectional area of the wave guide at the discontinuity, and a window closure for each said window permeable to electromagnetic wave propagation in the wave guide through said closure from one side of the discontinuity to the other.

DAVID GORDON CLIFFORD.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,093,567 McCullough Sept. 21, 1937 2,218,331 Etzrodt Oct. 15, 1940 2,298,335 Atlee Oct, 13, 1942 2,148,488 McEuen Feb. 28, 1939 2,407,690 Southworth Sept, 17, 1946 5o 2,407,069 Fiske Sept. 3, 1946 2,200,023 Dallenbach May 7, 1940 2,197,122 Bowen Apr, 16, 1940 FOREIGN PATENTS Number Country Date 484,144- Great Britain Nov. 29, 1937 

